github.com/prometheus/client_model v0.2.0: go.Metric

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/prometheus/client_model/go.Metric in pkg:golang/github.com/prometheus/client_model@v0.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/client_model@v0.2.0
Demonstrate these symbols/APIs:
  - github.com/prometheus/client_model/go.Metric

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:771ed2be6f63fe49ce58114d1e85590dcee1a39869eba1e4345a9cbf46e978d9","contract":["dto.Metric getter methods (GetLabel, GetGauge, GetCounter, GetSummary, GetUntyped, GetHistogram, GetTimestampMs) return nil or zero for nil and empty instances.","dto.Metric stores and retrieves labels, gauge metric value, and timestamp in milliseconds.","dto.Metric stores and retrieves counter metric value.","dto.Metric.Reset clears all fields back to zero values."],"goal":"verify github.com/prometheus/client_model/go.Metric in pkg:golang/github.com/prometheus/client_model@v0.2.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/client_model@v0.2.0"],"schemaVersion":1,"symbols":["github.com/prometheus/client_model/go.Metric"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","executionContext":"go","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/prometheus/client_model@v0.2.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/client_model@v0.2.0","symbols":["github.com/prometheus/client_model/go.Metric"],"verifierAdapter":"golang@1"}

module example.com/metric

go 1.22.0

require (
	github.com/golang/protobuf v1.5.4
	github.com/prometheus/client_model v0.2.0
)

require google.golang.org/protobuf v1.36.6 // indirect

github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
github.com/prometheus/client_model v0.2.0 h1:uq5h0d+GuxiXLJLNABMgp2qUWDPiLvgCzz2dUR+/W/M=
github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=

package main

import (
	"fmt"

	"github.com/golang/protobuf/proto"
	dto "github.com/prometheus/client_model/go"
)

func main() {
	labelName := "method"
	labelVal := "GET"
	gaugeVal := 123.45
	tsMs := int64(1700000000000)

	metric := &dto.Metric{
		Label: []*dto.LabelPair{
			{
				Name:  proto.String(labelName),
				Value: proto.String(labelVal),
			},
		},
		Gauge: &dto.Gauge{
			Value: proto.Float64(gaugeVal),
		},
		TimestampMs: proto.Int64(tsMs),
	}

	fmt.Printf("Metric label count: %d\n", len(metric.GetLabel()))
	if len(metric.GetLabel()) > 0 {
		fmt.Printf("Metric label: %s=%s\n", metric.GetLabel()[0].GetName(), metric.GetLabel()[0].GetValue())
	}
	if g := metric.GetGauge(); g != nil {
		fmt.Printf("Metric gauge value: %f\n", g.GetValue())
	}
	fmt.Printf("Metric timestamp ms: %d\n", metric.GetTimestampMs())

	metric.Reset()
	fmt.Printf("After reset, labels count: %d\n", len(metric.GetLabel()))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/client_model/go.Metric in pkg:golang/github.com/prometheus/client_model@v0.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/client_model@v0.2.0"
  ],
  "symbols": [
    "github.com/prometheus/client_model/go.Metric"
  ]
}

package test

import (
	"testing"

	"github.com/golang/protobuf/proto"
	dto "github.com/prometheus/client_model/go"
)

func TestMetricNilAndDefaults(t *testing.T) {
	var nilMetric *dto.Metric
	if got := nilMetric.GetLabel(); got != nil {
		t.Errorf("nilMetric.GetLabel() = %v, want nil", got)
	}
	if got := nilMetric.GetGauge(); got != nil {
		t.Errorf("nilMetric.GetGauge() = %v, want nil", got)
	}
	if got := nilMetric.GetCounter(); got != nil {
		t.Errorf("nilMetric.GetCounter() = %v, want nil", got)
	}
	if got := nilMetric.GetSummary(); got != nil {
		t.Errorf("nilMetric.GetSummary() = %v, want nil", got)
	}
	if got := nilMetric.GetUntyped(); got != nil {
		t.Errorf("nilMetric.GetUntyped() = %v, want nil", got)
	}
	if got := nilMetric.GetHistogram(); got != nil {
		t.Errorf("nilMetric.GetHistogram() = %v, want nil", got)
	}
	if got := nilMetric.GetTimestampMs(); got != 0 {
		t.Errorf("nilMetric.GetTimestampMs() = %v, want 0", got)
	}

	emptyMetric := &dto.Metric{}
	if got := emptyMetric.GetLabel(); got != nil {
		t.Errorf("emptyMetric.GetLabel() = %v, want nil", got)
	}
	if got := emptyMetric.GetGauge(); got != nil {
		t.Errorf("emptyMetric.GetGauge() = %v, want nil", got)
	}
	if got := emptyMetric.GetTimestampMs(); got != 0 {
		t.Errorf("emptyMetric.GetTimestampMs() = %v, want 0", got)
	}
}

func TestMetricWithLabelsAndGauge(t *testing.T) {
	labelName := "handler"
	labelVal := "prometheus"
	gaugeVal := 99.5
	ts := int64(1690000000123)

	metric := &dto.Metric{
		Label: []*dto.LabelPair{
			{
				Name:  proto.String(labelName),
				Value: proto.String(labelVal),
			},
		},
		Gauge: &dto.Gauge{
			Value: proto.Float64(gaugeVal),
		},
		TimestampMs: proto.Int64(ts),
	}

	labels := metric.GetLabel()
	if len(labels) != 1 {
		t.Fatalf("len(metric.GetLabel()) = %d, want 1", len(labels))
	}
	if labels[0].GetName() != labelName || labels[0].GetValue() != labelVal {
		t.Errorf("label mismatch: got name=%s val=%s, want name=%s val=%s",
			labels[0].GetName(), labels[0].GetValue(), labelName, labelVal)
	}

	gauge := metric.GetGauge()
	if gauge == nil {
		t.Fatal("metric.GetGauge() returned nil")
	}
	if gauge.GetValue() != gaugeVal {
		t.Errorf("gauge.GetValue() = %v, want %v", gauge.GetValue(), gaugeVal)
	}

	if metric.GetTimestampMs() != ts {
		t.Errorf("metric.GetTimestampMs() = %v, want %v", metric.GetTimestampMs(), ts)
	}
}

func TestMetricWithCounter(t *testing.T) {
	counterVal := 1500.0
	metric := &dto.Metric{
		Counter: &dto.Counter{
			Value: proto.Float64(counterVal),
		},
	}

	counter := metric.GetCounter()
	if counter == nil {
		t.Fatal("metric.GetCounter() returned nil")
	}
	if counter.GetValue() != counterVal {
		t.Errorf("counter.GetValue() = %v, want %v", counter.GetValue(), counterVal)
	}
}

func TestMetricReset(t *testing.T) {
	metric := &dto.Metric{
		Label: []*dto.LabelPair{
			{
				Name:  proto.String("service"),
				Value: proto.String("web"),
			},
		},
		Gauge: &dto.Gauge{
			Value: proto.Float64(10.0),
		},
		TimestampMs: proto.Int64(123456789),
	}

	metric.Reset()

	if got := metric.GetLabel(); got != nil {
		t.Errorf("after Reset(), metric.GetLabel() = %v, want nil", got)
	}
	if got := metric.GetGauge(); got != nil {
		t.Errorf("after Reset(), metric.GetGauge() = %v, want nil", got)
	}
	if got := metric.GetTimestampMs(); got != 0 {
		t.Errorf("after Reset(), metric.GetTimestampMs() = %v, want 0", got)
	}
}